Primary ovarian signet ring cell carcinoma: A rare case report.

Signet ring cell carcinoma (SRCC) of the ovary is most commonly metastatic from a primary lesion. Primary ovarian SRCC is rare, and the distinction between primary and metastatic SRCC of the ovary may be difficult. We herein present a case of primary SRCC of the ovary in a 54-year-old woman presenting with a right ovarian mass sized 20.5×16.5×11.5 cm. Total abdominal hysterectomy with bilateral salpingo-oophorectomy, partial omentectomy and incidental appendectomy were performed. Upon histological examination, mucinous carcinoma composed predominantly of signet ring cells was observed in the right ovary. The results of immunohistochemical examination included diffuse positivity for cytokeratin (CK)7 and CK20, but the tumor was negative for estrogen receptor, progesterone receptor, caudal type homeobox 2 and Wilms' tumor gene 1. A preoperative computed tomography (CT) scan of the abdomen and a postoperative positron emission tomography-CT scan did not reveal any suspicious extraovarian lesions. Based on the histological and clinicoradiological examinations, this case was diagnosed as a primary ovarian SRCC.